Telegraph system



1,624,393 Apnl 12 3 A, A. CLOKEY TELEGRAPH SYSTEM Filed May 29, 1925//7ve/7/0/. /4///.m/7 4. C/o/rey;

Patented Apr. 12, 1927.

UNITED STATES PATENT OFFICE.

nLLIsoN A. OLOKEY, or nurnnaron'n,

NEW JERSEY7 ASSIGNOB TO BELL TELEPHONE LABORATORIES, INCORPORATED, OFNEW YORK, N. Y., A. CORPORATION OF YORK.

Application filed May 29,

This invention relates to telegraph systerns and particularly to suchsystems in which signals are alternately transmitted and received.

An object of this invention is to provide -an economical and reliablerecordingsys. tem for alternate transmit-receive telegraph systems.

Loaded submarine cables are-often most 10 advantageously operatedsimplex, that is,

transmitting takes place in only one direction at a time. Therefore, itis necessary to reverse the direction of transmission in order to handletraflic in both directions. This reversal may be carried out eithermanually or automatically. At the end of-one period the transmittingapparatus "at one end is cut off and the receiving apparatus connected,while the reverse operation is carried on at the other end. When taperecorders are, employed, with such an arrangement, either forrecording'messages or for monitoring it is desirable in order to savetape to limit their operation during the period in which the side of thesystem to which they are connected is not in operation. .If the tapepulling motor is stopped entirely, blotting is likely to occur and it istherefore desirable to merely reduce the speed of the tape pulling motorduring the period of operation in which the recorder is not used. Inmultiplex printingcable telegraph systems, such, for example, as highspeed, sim-- plex systems arranged to transmit alternately in eachdirection over long, loaded cables, Where siphon recorders are employedfor monitoring, either transmitting or re- .ceiving, it is particularlydesirable to provide an arrangement "for automatically reducing thespeed of the tape pulling motor when the direction of operation ischanged by the switching mechanism. The speed of transmission in systemsof the type just re- 5 ferredto is several times as greatas in cabletelegraph systems heretofore in use and the saving in tape and othermaintenance costs,

. by the use of the invention is considerable. According to a feature ofthis invention D there is provided in an alternate transmit receivetelegraph system, an arrangement for slowing down the tape pullingmot-or of a recorder to a' speed-at which the ink will still flownormally, but at which consideri able tape is saved during the period ofop ratus to is reduced to four TELEGRAPH SYSTEM.

1926. Serial No. 112,464;

oration in which the recorder is not employed. v

This invention can be more readily understood by reference to thefollowingdetailed description in connection with the drawing which showsdiagrammatically one embodiment of the invention in an alternate trans=mit-receive cable telegraph system. Referring to this drawing shaft 4 isa portion of the shaft of the local switch of a multiplex printingtelegraph system arranged for simplex transmission alternately in eachdirection. This switch consists of a series of cams which open and closee ctrical contacts for changing the direction of. operation of thesystem from transmitting to receiving and vice versa. The print- ,ingtelegraph transmitting apparatus and receiving apparatus are indicatedschematicallyin thedrawing atT and R, res ectively. The switcl 1 cam 3on the shaft 4' serves in'one position to operate a polarized relay forconnecting the transmitting appathe transmission line or cable C and inanother position for connecting the receiving apparatus thereto. It willbe understood that the circuit arrangement in the drawing is very muchsimplified, as for example by the omission of means for amplifying andcorrecting the incoming signals before applying them to the receivingapparatus or to the monitoring arrangement next to be described.

A siphon recorder 5 is shown which is employed to monitor the operationof the cable during receiving, for example. This recorder makes a recordon a tape 6 by means of a. pen 7. The tape is drawn'by rollers 8 drivenby a direct current motor 9. For accurate monitoring the tape" is drivenat. a speed ofapproximately 60 feet per minute. i The speed of the motoris manually controlled to regulate the speed of the tape -or to reduceit when the system is operating in such a manner that accuratemonitdring is not required. The cam 10 mounted on the shaft of the localswitch operates a contact 15 to slow down the motor during thetransmitting period, when the recorder is not used. By means of thecircuit 'connected to the cam, ,the speed of the motor or five feet perminute, thus resulting in a considerable saving in tape. Powerissupplied from a battery 11 to the motor 9 which has a shunt field 12having one terminal connected directly to one brush and the otherthrough a resistance 13 to the other brush. A sliding contactor 14: isprovided by means of which the resistance 13 may be divided between thearmature and field circuits to control the speed of the motor. When acontactor is in the right hand position the resistance is all in thefield circuit and the motor runs at the highest speed while when thecontact is in the left hand position, the resistance is all in thearmature circuit and the motor runs at the lowest speed. A relay 16having an armature 17, back contact 18 and front contact 19 is providedfor reducing the speed of the motor during the transmitting period.During the receiving period of operation of the system in which the cam10 is in the position shown, connections are made from the negative poleof the battery 11 through armature 17, back contact 18 to the slidingcontactor 14, so that the motor operates normally and its speed can becontrolled by moving the contactor along the resistance 13. During thetransmitting period, connections are made from the positive pole of thebattery ll, ground, contact 15 of cam 10, winding of relay 16 to thenegative terminal of the battery actuating the relay 16 to make aconnection from the negative pole of the battery, through the armature17, front contact 15) to the left hand terminal of the resistance 13,slowing the motor down to its lowest speed and disconnecting the slidingcontactor 14.

It is understood that the embodiment of the invention above describedcan be variously modified without departing from the spirit of theinvention as defined in the appended. claims.

lVhat is claimed is:

1. In a telegraph terminal system ar-- ranged to operate in alternatetransmitting and receiving periods, a. recorder for use during one ofsaid periods, a tape on which a record is made by the operation of therecorder, a tape pulling motor, switching mechanism for controlling thedirection of operation of said system and means con trolled by saidswitching mechanism for reducing the speed of said motor during theother of said periods of operation.

2. A. combination according to the preceding claim in which the motor isan electrical motor having a shunt field winding and aresistancenormally in series therewith, and the speed reducing meanscomprises a relay and connections for removing said resistance I fromthe field winding circuit.

3.111 an alternate transmitareceivc telegraph system, a recorder havinga pen for monitoring during one period of operation, a tape on which arecord is made by said pen, a motor for pulling the tape through saidrecorder, a shunt field winding for said motor, a resistance normallyconnected in series with said field winding, switching mechanism forcontrolling thedirection of operation of said system, and means operatedby said switching mechanism for removing said resistance from the fieldwinding circuit during the other period of operation to reduce the speedof said motor.

4. An alternate transmit-receive telegraph system. a recorder having apen for monitoring during the receiving period, a tape on which a recordis made by said pen, a motor for pulling said tape. a shunt fieldwinding for said motor, a resistance connected in series with saidwinding, a source of current, connections from said source to said motorfor supplying current thereto, one ofsaid connections including avariable tap to said resistance whereby the portions of theq'osistanceincluded in the armature and field circuits of the motor are controlledto regulate the speed of the motor, switching mechanism for controllingthe direction of opera tion of said system, and means for reducing thespeed of said motor during the transmitting period, said meanscomprising a relay having contacts for connecting said resistance in thearmature circuit during the transmitting period.

In witness whereof, I hereunto subscribe my name this 27 day-of May, A.D. 1926.

ALLISON A. OLOKEY.

